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KeycloakApplication · Redhat

CVE-2021-20202

HIGH · 7.3 CVSS v3.1 Published 2021-05-12
Fix available
A fix is available. Upgrade to 13.0.0 or later.
See remediation →
75/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A flaw was found in keycloak. Directories can be created prior to the Java process creating them in the temporary directory, but with wider user permissions, allowing the attacker to have access to the contents that keycloak stores in this directory. The highest threat from this vulnerability is to data confidentiality and integrity.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Keycloak has a race condition vulnerability in its temporary directory handling. The Java process creates directories in /tmp with wider permissions than intended before the application populates them, allowing local unprivileged attackers to access or modify sensitive data stored in these temporary directories.

MitigationConfigure the temporary directory with restricted permissions (e.g., using sticky bits, proper umask settings) or redirect Keycloak to use a secured temp directory owned by the service account before the application starts.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
KeycloakApplication
Affected:< 13.0.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
Low

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Keycloak version
    Run 'keycloak --version' or check the version from the Keycloak admin console, or inspect the JAR/WAR file version metadata
    Affected if Version is below 13.0.0 (e.g., 12.x, 11.x, etc.)
  2. Identify temporary directory in use
    Check Keycloak configuration for 'java.io.tmpdir' system property or environment variables; also inspect running process with 'ps aux | grep keycloak' and check /proc/<pid>/environ for TMPDIR
    Affected if Temporary directory is set to /tmp or is not explicitly configured to a secured location
  3. Check current permissions on Keycloak temp directories
    List directories in /tmp that match Keycloak patterns (look for 'tmp' folders, 'jboss' or 'keycloak' named directories) and inspect their permissions with 'ls -la /tmp'
    Affected if Directories have permissions wider than 700 (e.g., 755, 777) or are owned by a different user than the Keycloak service account
  4. Verify umask applied to Keycloak process
    Check the umask setting in the Keycloak startup script (standalone.conf, startup scripts) or run 'cat /proc/<keycloak_pid>/status' to see the umask
    Affected if Umask is set to a permissive value like 000, 002, or 022 that allows group/other access to created directories
  5. Check for custom temp directory configuration
    Search Keycloak configuration files (standalone.xml, standalone-ha.xml, keycloak.conf) for 'tmpdir', 'tmp', or 'temp' directory path settings
    Affected if No custom secured temp directory is configured and the default /tmp location is in use

A user is affected if running Keycloak version below 13.0.0 with the default /tmp temporary directory and permissive directory permissions or umask settings.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to 13.0.0 or later
Fixed in 13.0.0
Interim mitigation

Configure the temporary directory with restricted permissions (e.g., using sticky bits, proper umask settings) or redirect Keycloak to use a secured temp directory owned by the service account before the application starts.

Fix this in Keycloak Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,800
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,880.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-20202 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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